What’s powerd by energy from earths intorior

Anna [14]

Considering the Hess's Law, the enthalpy change for the reaction is 221.8 kJ/mol.

Hess's Law indicates that the enthalpy change in a chemical reaction will be the same whether it occurs in a single stage or in several stages. That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when it occurs in a single stage.

In this case you want to calculate the enthalpy change of:

C₂H₄ (g) + 6 F₂ (g) → 2 CF₄ (g) + 4 HF (g)

which occurs in three stages.

You know the following reactions, with their corresponding enthalpies:

Equation 1: H₂ (g) + F₂ (g) → 2 HF (g) ∆H° = -79.2 kJ/mol

Equation 2: C (s) + 2 F₂ (g) → CF₄ (g) ∆H° = 141.3 kJ/mol

Equation 3: 2 C(s) + 2 H₂ (g) → C₂H₄ (g) ∆H° = -97.6 kJ/mol

Because of the way formation reactions are defined, any chemical reaction can be written as a combination of formation reactions, some going forward and some going back.

<h3 /><h3>FIRST STEP</h3>

First, to obtain the enthalpy of the desired chemical reaction you need one mole of C₂H₄ (g) on reactant side and it is present in first equation. Since this equation has one mole of C₂H₄ (g) on the product side, it is necessary to locate it on the reactant side (invert it).

When an equation is inverted, the sign of ΔH° also changes.

<h3>SECOND STEP</h3>

Now, you need 2 moles of CF₄ (g) on the product side. The second equation has 1 mole of CF₄ (g) on the product side, so it is necessary to multiply it by 2 to obtain 2 moles of CF₄ (g).

Since enthalpy is an extensive property, that is, it depends on the amount of matter present, since the equation is multiply by 2, the variation of enthalpy also.

<h3>THIRD STEP</h3>

Finally, you need 4 moles of HF (g) on the product side. The first equation has 2 moles of HF (g) on the product side, so it is necessary to multiply it by 2 to obtain 4 moles of the compound.

Since the equation is multiply by 2, the variation of enthalpy also is multiplied by 2.

<h3>SUMMARY</h3>

In summary, you know that three equations with their corresponding enthalpies are:

Equation 1: 2 H₂ (g) + 2 F₂ (g) → 4 HF (g) ∆H° = -158.4 kJ/mol

Equation 2: 2 C (s) + 4 F₂ (g) → 2 CF₄ (g) ∆H° = 282.6 kJ/mol

Equation 3: C₂H₄ (g) → 2 C(s) + 2 H₂ (g) ∆H° = 97.6 kJ/mol

Adding or canceling the reactants and products as appropriate, and adding the enthalpies algebraically, you obtain:

C₂H₄ (g) + 6 F₂ (g) → 2 CF₄ (g) + 4 HF (g) ΔH°= 221.8 kJ/mol

Finally, the enthalpy change for the reaction is 221.8 kJ/mol.

Learn more about molar enthalpy:

7 0

2 years ago

Rank these acids according to their expected pKa values.ClCH2COOHClCH2CH2COOHCH3CH2COOHCl2CHCOOHIn order of highest pka to lowes

Ilia_Sergeevich [38]

Answer:

CH₃CH₂CH₂COOH > CH₃CH₂COOH > ClCH₂CH₂COOH > ClCH₂COOH

Explanation:

Electron-withdrawing groups (EWGs) increase acidity by inductive removal of electrons from the carboxyl group.

Electron-donating groups (EDGs) decrease acidity by inductive donation of electrons to the carboxyl group.

The closer the substituent is to the carboxyl group, the greater is its effect.
The more substituents, the greater the effect.
The effect tails off rapidly and is almost zero after about three C-C bonds.

CH₃CH₂-CH₂COOH — EDG — weakest — pKₐ = 4.82

CH₃-CH₂COOH — reference — pKₐ = 4.75

ClCH₂-CH₂COOH — EWG on β-carbon— stronger — pKₐ = 4.00

ClCH₂COOH — EWG on α-carbon — strongest — pKₐ = 2.87

6 0

3 years ago

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Which is regarding enzyme inhbition

lys-0071 [83]

Explanation:

An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. ... Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used in pesticides.

7 0

3 years ago

The graph below shows the volume and the mass of four different substances at STP.

sladkih [1.3K]

The formula of density is mass / volume

This means that
- high mass, low volume = high density
- high mass, high volume = so-so
- low mass, high volume = low density

From the graph shown,
D has the lowest density because it has low mass yet high volume.

6 0

3 years ago

How many valence electrons does oxygen have? 2 4 6 8 10

Sphinxa [80]

8.................................

8 0

3 years ago

Read 2 more answers